The problems of electrolyte stratification, gas bubble formation on the electrodes, and a build-up of electrolyte impurities are well known in the art. Stratification occurs during battery charge/discharge cycling. The increase and decrease of the specific gravity of the electrolyte tends toward a buildup of higher specific gravity electrolyte toward the bottom of the cell and a build-up of lower specific gravity electrolyte toward the top of the cell. This non-uniformity of electrolyte specific gravity reduces the efficiency of the battery. Electrode gas bubble build-up occurs when hydrogen and oxygen gases tend to cling to the surface of the electrodes. This bubble formation reduces the surface area of the electrodes available for reaction with the electrolyte and reduces battery efficiency. Solid byproducts introduced into the electrolyte during the electro-chemical reactions occurring within the battery also tend to reduce battery efficiency.
Various attempts have been made to deal with these problems, but with only limited success. One popular method teaches the use of an over-voltage during charging to create gas bubbles which then tend to mix the stratified electrolyte as they rise to the top of the electrolyte. Hammer (U.S. Pat. No. 4,308,322) teaches a method of capturing overcharge gases and conducting the bubbles through a vertical conduit, creating a pump that transports high specific gravity electrolyte from the bottom of the battery cell to the top of the cell, thus reducing stratification. Ross (U.S. Pat. No. 4,842,963) teaches the external circulation of the electrolyte as well as filtration. This device, however, is designed for use with the zinc air battery with its built-in internal circulation capability. The design is not compatible with lead-acid batteries, nor does it provide for automatic system electrolyte quantity control or for recovery of the water after it has broken down into oxygen and hydrogen gases.